Define a Function $f : \mathbf { R } \longrightarrow \mathbf { R }$

Essay

Define a function $f : \mathbf { R } \longrightarrow \mathbf { R }$ as follows: for all real numbers $x$ ,
$$f ( x ) = 16 x - 5 .$$
Then $f$ is both one-to-one and onto. Find the inverse function $f ^ { - 1 }$ .